Guam-sized iceberg drifts away from Antarctic glacier

WASHINGTON -- Scientists are watching an iceberg bigger than the island of Guam as it slowly moves away from an Antarctic glacier.

NASA scientist Kelly Brunt said it is more a wonder than a worry and is not a threat to shipping or sea-level rise.

Brunt said the iceberg, named B-31, is about 255 square miles, roughly six times as big as Manhattan and as much as 1,600 feet thick. It broke off from the critical Pine Island Glacier last fall and researchers have been watching it move away ever since.

She said it is completely natural for icebergs to split off from glaciers in Antarctica, however this calving does shrink the Pine Island Glacier beyond its 30-year normal.

According to the NASA Earth Observatory website, Grant Bigg of the University of Sheffield is leading a research team that has been tracking the iceberg.

"We are doing some research on local ocean currents to try to explain the motion properly. It has been surprising how there have been periods of almost no motion, interspersed with rapid flow," Bigg said. "There were a couple of occasions early on when there might have been partial grounding or collisions with the seafloor, as B31 bounced from one side of the Bay to the other."